Spey salmon fry index mainstem surveys 2017

Conditions have been perfect this week for the mainstem salmon fry index surveys, low water being one of the most desirable factors. Therefore we started the 2017 surveys on Monday making good progress reaching as far upstream as Tulchan by the end of play today. The salmon fry index surveys consist of 3 minute timed surveys, primarily in shallow run riffle habitat although for continuity and historical reasons some of the sites are equally suited to parr. We try to do these surveys at the same time of year keeping as many variables as consistent as possible e.g. same sites, staff and equipment.

The draft results to date for salmon fry are shown in the table below (for those not familiar with the colour coding black is absent, red the bottom 20%, followed by amber, yellow, light green, with dark green for the top 20% of Spey results 2012 to 2016)

Spey mainstem salmon fry index results to date. The results from the lower half of the river have been good with all sites in the moderate to excellent categories. The mean salmon fry count from the sites surveyed so far is the highest in the sequence. Tulchan D remains the only site with 100% dark green classification, although the counts were actually below average for that site today, perhaps a consequence of the unusually good parr counts (see below). (Note that the Phones & Lower Pitchroy sites have still to be surveyed)

These initial results are encouraging although not unexpected following an excellent spawning and relatively benign flows overwinter. The 8ft spate in early June does not seem have had too much of an impact; thankfully. A feature this year is the consistency of the results, perhaps this is a consequence of the spate which may have evened out the distribution of the fry from their initial clumped distribution arising from proximity to the redds.

The situation for parr is a bit different with low parr counts in the lower reaches, improving greatly as we progressed upstream.

Spey salmon fry index parr counts. Although these surveys are primarily intended to assess salmon fry parr are also captured. Parr were notable by their relative absence in the lower sites but from Aberlour upstream the results are much better. The salmon parr counts from two of the four Tulchan sites were the best recorded with results from the other two being the second highest. The low parr counts in the lower sites are likely to be a consequence of the low fry counts in the river downstream of the Avon confluence in 2016 – remember Storm Frank?

A sample of the typical mixed catch of fry and parr from the Tulchan, Ballindalloch and Knockando sites today.

The June 2017 spate may not have affected fry counts too severely but large scale riverbed movements were apparent almost everywhere downstream of the Avon. The locations of one or two of the survey sites has to be moved slightly due to the riverbed movements. This is not critical with this type of survey where we follow the habitat rather than fixed landmarks. At other sites the surveys may have been completed in the same location but the habitat had changed due to sediment deposition.

Recent deposits of cobbles in a survey site at Knockando. These fresh looking cobbles are recent arrivals, formerly this site was dominated by boulder habitat, some of which protrude above the new cobbles. It was much easier wading than usual today but these cobbles are likely to move during the next few spates.

It doesn’t take long for nature to colonise empty habitat as can be seen by the number of simuliidae larvae on this recently deposited rock.

Few trout have been recorded so far during these surveys, no surprise as they generally spawn in the tributaries, but there does seem to be more eels than in recent years. In the first two sites elvers were present in abundance with the size distribution increasing quickly as we progressed upstream. The concern regarding low eel numbers in recent years seems to have abated a little, which in my view is a good thing. I like to see everything in the river doing well, well nearly everything! Eels, like salmon, are ocean migrants, and whilst their life cycles are quite different both species depend on the health and suitability of a range of different habitat types.

Ultimately today turned out to be a good day; we made good progress with our surveys, spent some quality time with the new Tulchan factor and ghillies and there were lots of juveniles to be counted. Not bad at all considering I was on the point of going back to bed when I got up this morning. A summer cold is a bind but once I was up and about it was forgotten about. I even did some maintenance on the pick-up tailgate – it shuts now, the old 3 in 1 is great stuff.